CD4 and neoplasm: As a well‐known immunosuppressive molecule, TGF‐β inhibits the body's antitumor immune response in inflammatory and tumor environments in various ways, including inhibiting the activities of cytotoxic T lymphocytes (CTLs), T follicular helper cells, and NK cells; preventing the differentiation of CD4+ T cells into Th1 and Th2 cells; and inducing Treg and Th17 production [65, 66, 67].